Mycobacterium avium ssp.
paratuberculosis (MAP)
infection in cattle causes significant economic losses to the dairy and beef industries resulting from reduced productivity, premature culling and mortality. Bovine
Dectin-1, an important pattern recognition molecule that is able to generate a proinflammatory response by acting alongside
Toll like receptor (TLR) signaling, is known to co-operate with TLR2 to specifically activate a macrophage proinflammatory response against mycobacterial
infections. Therefore, the goal of this study was to identify single nucleotide polymorphisms (SNPs) in the gene encoding bovine
Dectin-1 (CLEC7A) and to assess their association with susceptibility to MAP
infection in dairy cattle. Blood and milk samples, collected from commercial dairy operations, were tested for MAP
infection using blood and milk ELISAs and a resource population consisting of 197 infected and 242 healthy cattle was constructed. Pooled
DNA was used for sequencing and eight single nucleotide polymorphisms (SNPs) were identified. Identified SNPs were genotyped on the resource population using the
iPLEX MassARRAY system and statistical analysis was performed using logistic regression fitting the additive and dominance effects of each SNP in the model. Out of a total of eight identified SNPs, five were successfully genotyped, and three out of these five SNPs were found to be in complete linkage. Statistical analysis revealed a strong association between a non-synonymous SNP c.589A>G (p=0.008), and MAP
infection status of the resource population inferred by seropositivity in MAP antibody specific ELISAs. This SNP c.589A>G was located in the geneic region that encodes the
carbohydrate recognition domain of bovine
Dectin-1. Therefore, further investigation of its functional relevance is warranted.